<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="./lib/vue.min.js"></script>
    <style>
        .ball{
            width: 15px;
            height: 15px;
            background-color: red;
            border-radius: 50%;
        }


    </style>
</head>
<body>
    <div id="app">
        <input type="button" value="下落" @click = "flag = !flag">
        
        <transition
          @before-enter = "beforeEnter"
          @enter = "enter"
          @after-enter = "afterEnter">
            <div class="ball" v-show = "flag"></div>
        </transition>
    </div>
    
    <script>
        var vm = new Vue({
            el:"#app",
            data:{
                flag: false
            },
            methods: {
                beforeEnter(el) {
                    el.style.transform = "translate(0, 0)"
                },
                enter(el, done) {
                    el.offsetWidth

                    el.style.transform = "translate(150px, 450px)"
                    el.style.transition = "all 1s ease"

                    done()
                },
                afterEnter(el) {
                    this.flag = !this.flag
                    //只能使用上面一种，下面这种有问题
                    //el.style.opacity = 0
                }          
            }
        })
    </script>
</body>
</html>